Catholic Encyclopedia - An old, multi-volume work published in New York in the early part of the twentieth century. It drew upon the expertise of leading scholars of the day and is still very useful, especially for historical studies.
New Catholic Encyclopedia (available online from Saint Mary's College Library) - A much more concise work than the old Catholic Encyclopedia but with the merit of reflecting changes in ecclesiology and culture after the Second Vatican Council.
Catholic Resources for Bible, Liturgy, Art, and Theology - A website managed by a Jesuit priest of Orange County, California. It specializes in links for Bible, Liturgy, Art, and Theology.
The Mary Page at the University of Dayton - The University of Dayton, operated by the Society of Mary (the Marianists), is a great center for the study of Saint Mary, the Blessed Mother and patroness of our College.
Saint Thomas Aquinas, Summa Theologica - Pope Leo XIII, in Aeterni Patris, 4 August 1879, recommended Saint Thomas as the model for the pursuit of higher learning. He said of him the following, "he is rightly and deservedly esteemed the special bulwark and glory of the Catholic faith. With his spirit at once humble and swift, his memory ready and tenacious, his life spotless throughout, a lover of truth for its own sake, richly endowed with human and divine science, like the sun he heated the world with the warmth of his virtues and filled it with the splendor of his teaching." The link here is to Aquinas's compendium of theology, left incomplete at the time of his death.
Online Theology Library of Spring Hill College - The Theology Department of Spring Hill College in Mobile, Alabama, has compiled a remarkable library of resources for study. The site is well worth browsing.